Study: Protease Inhibitor Monotherapy Does Not Limit Future Treatment Options

November 24, 2015

Study: Protease Inhibitor Monotherapy Does Not Limit Future Treatment Options

A recent study published in The Lancet HIV provides evidence that HIV maintenance therapy with a provider-selected boosted protease inhibitor (PI) regimen does not increase the risk of drug resistance and thus preserves future treatment options. But questions remain as to whether PI-monotherapy could be a clinically useful and relevant long-term HIV maintenance strategy.

Multiple HIV drugs -- from different classes -- are currently recommended for the treatment of HIV because combination therapy increases drug potency and reduces the likelihood that drug-resistant mutations will occur (mutations are less likely to crop up when viral loads are well-controlled). According to the study authors, people with controlled viral loads may benefit from protease inhibitor monotherapy (PI-monotherapy) more than combination therapy if monotherapy is less expensive and if the risk that drug-resistant mutations will develop is low.

Once viral loads are well-controlled, it's possible that combination therapy is no longer needed if a protease inhibitor can be substituted, suggest Nicholas Paton, MD, FRCP and fellow authors of the current study report.

"Protease inhibitors are potent, with a high genetic barrier to resistance, and are the only drugs that act at many steps of the HIV lifecycle, thus having the potential for use alone as monotherapy," Paton and colleagues say.

To test their theory, the research team randomized 587 people with undetectable viral loads stable on a combination therapy regimen for at least three months to either maintain their ongoing medication regimen or switch to a boosted PI-monotherapy. They measured viral loads, drug adherence, CD4 cell count, drug resistance mutations and drug- and disease-related health events over the following three to five years (depending on when each participant was recruited and enrolled into the study), with a median follow-up duration of 44 months.

Over half (58%) of participants in the PI-monotherapy group were still on monotherapy at the end of the study. Most of the 118 people who switched from PI-monotherapy to combination therapy during the study did so because of viral rebound (67%) and toxicity (14%).

This excerpt was cross-posted with the permission of Read the full article.

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